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Hey all in the future I’m gonna be resurrecting a 1968 C-10 Chevy truck. Im torn between 2 engines for my build. Im thinking either a 383 stroker or 327. Can anyone help me on my decision and have recommendations thanks. Mike
 

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383 all day every day and twice on sunday.

It's the same engine but with more bore and stroke. No brainer. The only reason to choose a 327 would be if you're doing a numbers-match restoration.
Thanks Curtis now I have that out the way I have heard that a person can start out building this engine with a 4 bolt main 350 block is this true? And if so what would be your recommendations to get me started
 

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You can build a 383 with nearly any 4" bore small block. Some are better than others (more thickness in the cylinder walls, better clearance on the pan rail, etc) but pick one and go. 2 bolt mains would be fine up to about 450 hp/6000 rpm if it's built right.

4 bolt mains are stronger than 2 bolt but only by a small margin. The strongest is a 2-bolt main that is drilled/tapped for 4-bolt caps, and if you shop smartly you can sometimes score a 2-bolt block that is so much cheaper than a 4-bolt that it saves you enough money to have it drilled for 4 bolts.
 

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383 all the way, More cubes means more power, more power means more burnout.
Common misconception. More cubes means more torque. Assuming that the same parts/specs are used, a 327 and a 383 will make the same exact power, but the 383 makes more torque and at a lower peak RPM. The bigger cubes allows you to make more power within the same RPM range if you bump up the parts to match it.
 

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Also important to note... a 383 comes from the 3.75" stroke and 4.030" bore. I always suggest only boring it out to what you need. If you find a good block that needs no overbore, don't just hog it out for the sake of reaching 383 cubes. I always suggest the minimum overbore needed so it has more life left for the next person. A stock bore with 3.75" stroke works out to 377, and it won't make any real-life difference in the performance.
 

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When selecting a block, I strongly suggest a later roller-cam block. Roller cams are infinitely better in almost every aspect, and while you can buy parts to retrofit a roller cam in an older block, it's stoopid expensive.
 

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Common misconception. More cubes means more torque. Assuming that the same parts/specs are used, a 327 and a 383 will make the same exact power, but the 383 makes more torque and at a lower peak RPM. The bigger cubes allows you to make more power within the same RPM range if you bump up the parts to match it.
When I say power I usually mean torque. I fully agree with you about same horse power being the same and the only difference is torque. Really it comes down to price.
 

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When selecting a block, I strongly suggest a later roller-cam block. Roller cams are infinitely better in almost every aspect, and while you can buy parts to retrofit a roller cam in an older block, it's stoopid expensive.
Thanks man that gives me a lot to think about. I’ve heard double hump heads are ideal for this particular build what’s your thoughts?
 

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Nothing all that wrong with double humps but their port volume is low for a 283 and they are a bit obsolete in chamber effectivness. Basically the L31 Vortec head’s of 1996 up on Gen I engines totally changed the torque and power equation. Depending on what previous head’s your comparing to and what cam is used modern head’s like the L31 Vortec are a 20 to 60 ft lbs and like horsepower bolt on. These days seekers after power do not bother with camel humps, though not as bad as SMOG head’s their best days are behind them.

As a data point a stock 350 short block with a Comp XE268H cam and L31 head’s at about 9.5:1 compression with an Edelbrock RPM intake or other decent dual plane high rise intake with a carb from 650 to 750 cfm and long tube headers will put down 400 ft lbs and 380 hp. Back in the day it took a 350 with camel humps with 10.5:1 compression and Rochester fuel injection to come close to that as a Corvette top option engine with a solid lifter cam.

With a little tweaking buy a gentle port cleaning, stiffing up the valve train with 7/16 studs and roller 1.6 ratio rockers you can inch the torque up around 430 ft lbs and power to 410 ponies.

Since your building from the floor up if you use aluminum aftermarket head’s like the inexpensive imports with either a D dish piston and 64cc chambers or a flat top piston with 76cc modern chamber head’s you can expect to see torque to remain about 420-430 ft lbs with power up to about 430 to 440 ponies. The above example being a very streetable 350.

For a like built 383 you can expect to the advantages of 33 more cubic inches.

There is a lot more to this in the details so don’t go rushing to buy parts just yet. 383’s can be built using the 400 5.54 inch rod and piston set, or the more GM standard 5.7 rod and piston set or the 6 inch rod and piston set the latter often also allows internal balancing. Cap screw rods generally don’t require near the block or cam clearancing that bolt and nut style rods do.

4 bolt blocks are better suited to high loading whether that’s torque use in a heavy truck or high RPM in a car. Below those points a 2 bolt block is fine. Aluminum head’s require either the block be zero decked or the use of a raised compression height piston (stay away from rebuilder pistons these are lowered compression height to restore stock compression ratios on decked blocks) that is not the direction we’re going in.

When it comes to boring and decking the less casting removed the stronger the remains. Modern production castings are thin wall they do not take kindly to material removal. Generally .040 is max on bores most 383’s are .030. Decking is often .025, but if you can find a gasket that nets close to the .040 magic squish clearance on less cutting the better. Keep in mind that with aluminum head’s their best sealing is with a composite gasket for which the thinnest you will find will be .026 to .028 compressed. Cast iron head’s can use shim gaskets which run about .015 to .019 compressed so zero decking usually isn’t required with iron head’s but in terms of compression while modern chambered head’s like the L31 allow the compression to be pushed over 9:1 aluminum allows if not demands a ratio higher. So you need to do some modern planning and math, not just picking up old time hotrod lore about camel hump head’s being universally desireable.

A roller block is nice it works the expensive cam options as factory roller set ups are very good and a lot less expensive than aftermarket retro set ups. These factory roller blocks also use the 1 piece rear seal which is way more oil tight than the old two piece seal. These cranks use a smaller bolt circle which drives a new flywheel or flex plate depending on your tranny type.

Kits are nice but you need to understand the path that each kit will take you down, they are not all the same in details you will need to wrestle.

Bogie
 

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First let me say that a 327 vs a 383 does not equal the same HP but greater torque. There are lots of ways to twist that answer, but the basic truth is that an engine can ONLY produce torque......not HP. A smaller engine may turn a higher rpm and result in a higher (maybe/maybe not) HP because of additional RPMs. You aren't concerned about that in a street driver, because you don't want to wind your engine that high. Think of it like this. First you have to produce torque with the engine. Then you plug that torque into a formula with the rpm and you CALCULATE the HP result. You did NOT make HP, you made torque. Thats why a larger displacement engine that produces more torque at a given rpm will result in more HP. This is in a naturally aspirated engine.

If you look at any dyno charts, you will notice that HP and Torque cross paths at 5252 rpms. By then the Torque is on the downswing, so how does the HP continue rising?

The answer is that the increase in RPMs has a greater effect than the loss of torque output. HP=Torque X RPM / 5252

400
lbs/ft torque X 2000 RPMs / 5252 ......... 400 x 2000 = 800,000 divided by 5252 = 152 HP

300 lbs/ft torque X 2000 RPMs / 5252 ......... 300 x 2000 = 600,000 divided by 5252 = 114 HP

400 lbs/ft torque X 5000 RPMs / 5252 .......... 400 x 5000 = 2,000,000 divided by 5252 = 380 HP

300 lbs/ft torque X 5000 RPMs / 5252.......... 300 x 5000 = 1,500,000 divided by 5252 = 285 HP

From looking at the examples above you can see that the engine capable of producing the most torque at a given rpm will produce the most HP at that rpm.
Generally this gives rise to the statement that
"There is no replacement for displacement". For a street driven hot rod that is basically true. Formula 1 racing engines have very small displacement yet produce phenominal HP......but they may turn upwards of 15,000 rpms and don't have to last very long. To a lesser extent a smaller version of a smallblock Chevy can be made to produce equal or greater HP than a larger version ........but not when using essentially the same components. With a larger engine you can generally produce more torque at each rpm.

Something that you should realize is that its not the "HP at maximum rpm" thats important in a daily driver, even though thats what everyone likes to brag about.

If you take part in any acceleration test/race, you should realize that its average HP thats important. By that I mean that you only spend a moment at 5500+ rpms. You also have to produce more power at all the lower rpms. If it takes 12 seconds to accelerate thru a quarter mile, you need to break it into say 1/10 second parts and make the most HP at each of these 1/10 second increments.
The person/engine whose total HP for the 12 seconds will most likely win the race. There are some other considerations and ways to increase torque in a smaller displacement so that it rivals the larger engine, but you will give up a lot of driveability to get there. (Note: Yes you can build an engine so large that it becomes rpm limited, but generally not a problem with a 383)

I would look at using the larger displacement and lowering the compression to 9.0/9.5 range so you can run regular gas or premium. You will not loose that much HP/Torque by doing so. Comp ratios above 10:1 often become problematic and usually have less valve clearance. I would use roller rockers that have a higher ratio than stock and some quality behive springs on aftermarket aluminum heads. ( Note: Factory engines these days run higher compression ratios but they have computer controlled outputs and knock sensors and millions of dollars in engineering) Forget the double hump heads. Costs more to rebuild them right than they are worth and many are beyond being rebuilt these days.



Last of all, a cam that may be "over cammed" for a 327 may be perfect for a 383 which means you can build the larger engine to produce more HP per cubic inch while still having a milder engine. There are limits to engine sizes which are useful, even though guys like to brag about size and Hp.
 

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Thanks man that gives me a lot to think about. I’ve heard double hump heads are ideal for this particular build what’s your thoughts?
Meh. Double humps were OK in 1965. 062 or 906 Vortec heads would work nicely as a budget option, but I agree... something aftermarket in the 195cc port range would be better depending on the cam choice.
 

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budget? If you can afford a 383- by all means thats the ticket. If you arent adding power booster 4 bolts wont be any benefit.. (its a 2 bolt main which as ive mentioned with required expensive linked lifters to go roller unless you want to stay flat tappet cam).. See my post regarding your 383 thread. All the info is in there.

Bear in mind a 383 budget consists of:

  • 383 crank or kit (incl matched rot assembly parts) depending on what route you go
  • cam/heads: get ready to buy pushrods, springs, shims, guideplates, rockers, studs - it adds up!
fwiw - I had a stock bottom end L31, 3000 stall, GM hotcam, stock vortec heads modified only for more valve lift, stock rockers/pushrods, dual plane, quadrajet, LT headers and a 2-1/4 exhaust i scrounged off a 90s mustang at the yard.

That car would take off like a ROCKET when I mashed it.. and it was CHEAP as chips. If you get the combo right trust me a well tuned and setup 350 can smoke a 383 too - bearing in mind I had the low tension vortec piston/ring setup - that REALLY makes a difference! You can rotate an assembled bottom end with 2 fingers on a ratchet. Try that with sbc 3/16 rings on a honed bore!

Just an option - we dont know how much $ you want to spend - bear in mind going up from a 400hp 350 for a street toy means upgraded tranny too, and now the budget has jumped big time. My stock 2004R held up for 10 years of burnouts, mashing it and 3 cross country trips @ 23mpg..
 

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Here is a picture of a dyno pull on a 500 Cadillac with just a very mild cam installed........basically just a minor upgrade over a stock Cad. Look at where it generates 200 hp and 300 hp and how flat the torque curve is. 327 Chevy isn't going to compare to how this engine makes the truck driveable. 500 lbs/ft from 2000 rpm till almost 5,000 rpms.
Rectangle Font Parallel Technology Screenshot
 

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Here is a picture of a dyno pull on a 500 Cadillac with just a very mild cam installed........basically just a minor upgrade over a stock Cad. Look at where it generates 200 hp and 300 hp and how flat the torque curve is. 327 Chevy isn't going to compare to how this engine makes the truck driveable. 500 lbs/ft from 2000 rpm till almost 5,000 rpms.
View attachment 619080
Dear god in heaven.... let me at those heads with a die grinder.
 

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The first one I'm building should easily exceed this engine across the board and still be very streetable. With multi point injection and 6th gear overdrive, I think I can even get decent gas mileage on a trip. My 49 Chevy will have a tow hitch too.
 

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Last caddy I built I actually used a smaller cam than stock. Pocket ported intake, fully ported exhaust. I estimated 275hp, but I couldn't find a dyno that would hold it. As soon as you rolled on the throttle at even 1000 rpms, it just overpowered the brake on the dyno. One guy said, "well the dyno can hold 600, so you're somewhere north of that."

All I know is that it was all done by 4250. I basically built a diesel.
 

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Yes they were designed so that they only reved about 4500 (on a good day). Rocker arms need replacement to allow them to rev somemore. I don't plan on anything over about 5200/5500. I've got some professionally ported heads with larger valves and better springs that I picked up with about 10K on them. Probably work them a little more myself. Going to use a roller cam, roller rockers and about 9:1 compression. Modified the oiling system some. Probably forged pistons but not against hyperutectic. The valve train upgrades really wake these engines up and you can keep low compression and run regular gas. I'm gonna shoot for 500 hp, but I'll be happy with anything over 450.
 
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